diff --git a/daemons/attrd/attrd_corosync.c b/daemons/attrd/attrd_corosync.c
index 79e496ae85..39f465f35d 100644
--- a/daemons/attrd/attrd_corosync.c
+++ b/daemons/attrd/attrd_corosync.c
@@ -1,582 +1,582 @@
 /*
  * Copyright 2013-2022 the Pacemaker project contributors
  *
  * The version control history for this file may have further details.
  *
  * This source code is licensed under the GNU General Public License version 2
  * or later (GPLv2+) WITHOUT ANY WARRANTY.
  */
 
 #include <crm_internal.h>
 
 #include <errno.h>
 #include <stdbool.h>
 #include <stdint.h>
 #include <stdlib.h>
 
 #include <crm/cluster.h>
 #include <crm/cluster/internal.h>
 #include <crm/common/logging.h>
 #include <crm/common/results.h>
 #include <crm/common/strings_internal.h>
 #include <crm/msg_xml.h>
 
 #include "pacemaker-attrd.h"
 
 extern crm_exit_t attrd_exit_status;
 
 static void
 attrd_peer_message(crm_node_t *peer, xmlNode *xml)
 {
     const char *election_op = crm_element_value(xml, F_CRM_TASK);
 
     if (election_op) {
         attrd_handle_election_op(peer, xml);
         return;
     }
 
     if (attrd_shutting_down()) {
         /* If we're shutting down, we want to continue responding to election
          * ops as long as we're a cluster member (because our vote may be
          * needed). Ignore all other messages.
          */
         return;
 
     } else {
         pcmk__request_t request = {
             .ipc_client     = NULL,
             .ipc_id         = 0,
             .ipc_flags      = 0,
             .peer           = peer->uname,
             .xml            = xml,
             .call_options   = 0,
             .result         = PCMK__UNKNOWN_RESULT,
         };
 
         request.op = crm_element_value_copy(request.xml, PCMK__XA_TASK);
         CRM_CHECK(request.op != NULL, return);
 
         attrd_handle_request(&request);
         pcmk__reset_request(&request);
     }
 }
 
 static void
 attrd_cpg_dispatch(cpg_handle_t handle,
                  const struct cpg_name *groupName,
                  uint32_t nodeid, uint32_t pid, void *msg, size_t msg_len)
 {
     uint32_t kind = 0;
     xmlNode *xml = NULL;
     const char *from = NULL;
     char *data = pcmk_message_common_cs(handle, nodeid, pid, msg, &kind, &from);
 
     if(data == NULL) {
         return;
     }
 
     if (kind == crm_class_cluster) {
         xml = string2xml(data);
     }
 
     if (xml == NULL) {
         crm_err("Bad message of class %d received from %s[%u]: '%.120s'", kind, from, nodeid, data);
     } else {
         crm_node_t *peer = crm_get_peer(nodeid, from);
 
         attrd_peer_message(peer, xml);
     }
 
     free_xml(xml);
     free(data);
 }
 
 static void
 attrd_cpg_destroy(gpointer unused)
 {
     if (attrd_shutting_down()) {
         crm_info("Corosync disconnection complete");
 
     } else {
         crm_crit("Lost connection to cluster layer, shutting down");
         attrd_exit_status = CRM_EX_DISCONNECT;
         attrd_shutdown(0);
     }
 }
 
 /*!
  * \internal
  * \brief Override an attribute sync with a local value
  *
  * Broadcast the local node's value for an attribute that's different from the
  * value provided in a peer's attribute synchronization response. This ensures a
  * node's values for itself take precedence and all peers are kept in sync.
  *
  * \param[in] a          Attribute entry to override
  *
  * \return Local instance of attribute value
  */
 static attribute_value_t *
 broadcast_local_value(const attribute_t *a)
 {
     attribute_value_t *v = g_hash_table_lookup(a->values, attrd_cluster->uname);
     xmlNode *sync = create_xml_node(NULL, __func__);
 
     crm_xml_add(sync, PCMK__XA_TASK, PCMK__ATTRD_CMD_SYNC_RESPONSE);
     attrd_add_value_xml(sync, a, v, false);
-    attrd_send_message(NULL, sync);
+    attrd_send_message(NULL, sync, false);
     free_xml(sync);
     return v;
 }
 
 /*!
  * \internal
  * \brief Ensure a Pacemaker Remote node is in the correct peer cache
  *
  * \param[in] node_name  Name of Pacemaker Remote node to check
  */
 static void
 cache_remote_node(const char *node_name)
 {
     /* If we previously assumed this node was an unseen cluster node,
      * remove its entry from the cluster peer cache.
      */
     crm_node_t *dup = pcmk__search_cluster_node_cache(0, node_name);
 
     if (dup && (dup->uuid == NULL)) {
         reap_crm_member(0, node_name);
     }
 
     // Ensure node is in the remote peer cache
     CRM_ASSERT(crm_remote_peer_get(node_name) != NULL);
 }
 
 #define state_text(state) pcmk__s((state), "in unknown state")
 
 /*!
  * \internal
  * \brief Return host's hash table entry (creating one if needed)
  *
  * \param[in,out] values Hash table of values
  * \param[in]     host   Name of peer to look up
  * \param[in]     xml    XML describing the attribute
  *
  * \return Pointer to new or existing hash table entry
  */
 static attribute_value_t *
 attrd_lookup_or_create_value(GHashTable *values, const char *host,
                              const xmlNode *xml)
 {
     attribute_value_t *v = g_hash_table_lookup(values, host);
     int is_remote = 0;
 
     crm_element_value_int(xml, PCMK__XA_ATTR_IS_REMOTE, &is_remote);
     if (is_remote) {
         cache_remote_node(host);
     }
 
     if (v == NULL) {
         v = calloc(1, sizeof(attribute_value_t));
         CRM_ASSERT(v != NULL);
 
         pcmk__str_update(&v->nodename, host);
         v->is_remote = is_remote;
         g_hash_table_replace(values, v->nodename, v);
     }
     return(v);
 }
 
 static void
 attrd_peer_change_cb(enum crm_status_type kind, crm_node_t *peer, const void *data)
 {
     bool gone = false;
     bool is_remote = pcmk_is_set(peer->flags, crm_remote_node);
 
     switch (kind) {
         case crm_status_uname:
             crm_debug("%s node %s is now %s",
                       (is_remote? "Remote" : "Cluster"),
                       peer->uname, state_text(peer->state));
             break;
 
         case crm_status_processes:
             if (!pcmk_is_set(peer->processes, crm_get_cluster_proc())) {
                 gone = true;
             }
             crm_debug("Node %s is %s a peer",
                       peer->uname, (gone? "no longer" : "now"));
             break;
 
         case crm_status_nstate:
             crm_debug("%s node %s is now %s (was %s)",
                       (is_remote? "Remote" : "Cluster"),
                       peer->uname, state_text(peer->state), state_text(data));
             if (pcmk__str_eq(peer->state, CRM_NODE_MEMBER, pcmk__str_casei)) {
                 /* If we're the writer, send new peers a list of all attributes
                  * (unless it's a remote node, which doesn't run its own attrd)
                  */
                 if (attrd_election_won()
                     && !pcmk_is_set(peer->flags, crm_remote_node)) {
                     attrd_peer_sync(peer, NULL);
                 }
             } else {
                 // Remove all attribute values associated with lost nodes
                 attrd_peer_remove(peer->uname, false, "loss");
                 gone = true;
             }
             break;
     }
 
     // Remove votes from cluster nodes that leave, in case election in progress
     if (gone && !is_remote) {
         attrd_remove_voter(peer);
 
     // Ensure remote nodes that come up are in the remote node cache
     } else if (!gone && is_remote) {
         cache_remote_node(peer->uname);
     }
 }
 
 static void
 record_peer_nodeid(attribute_value_t *v, const char *host)
 {
     crm_node_t *known_peer = crm_get_peer(v->nodeid, host);
 
     crm_trace("Learned %s has node id %s", known_peer->uname, known_peer->uuid);
     if (attrd_election_won()) {
         attrd_write_attributes(false, false);
     }
 }
 
 static void
 update_attr_on_host(attribute_t *a, const crm_node_t *peer, const xmlNode *xml,
                     const char *attr, const char *value, const char *host,
                     bool filter, int is_force_write)
 {
     attribute_value_t *v = NULL;
 
     v = attrd_lookup_or_create_value(a->values, host, xml);
 
     if (filter && !pcmk__str_eq(v->current, value, pcmk__str_casei)
         && pcmk__str_eq(host, attrd_cluster->uname, pcmk__str_casei)) {
 
         crm_notice("%s[%s]: local value '%s' takes priority over '%s' from %s",
                    attr, host, v->current, value, peer->uname);
         v = broadcast_local_value(a);
 
     } else if (!pcmk__str_eq(v->current, value, pcmk__str_casei)) {
         crm_notice("Setting %s[%s]: %s -> %s "
                    CRM_XS " from %s with %s write delay",
                    attr, host, pcmk__s(v->current, "(unset)"),
                    pcmk__s(value, "(unset)"), peer->uname,
                    (a->timeout_ms == 0)? "no" : pcmk__readable_interval(a->timeout_ms));
         pcmk__str_update(&v->current, value);
         a->changed = true;
 
         if (pcmk__str_eq(host, attrd_cluster->uname, pcmk__str_casei)
             && pcmk__str_eq(attr, XML_CIB_ATTR_SHUTDOWN, pcmk__str_none)) {
 
             if (!pcmk__str_eq(value, "0", pcmk__str_null_matches)) {
                 attrd_set_requesting_shutdown();
 
             } else {
                 attrd_clear_requesting_shutdown();
             }
         }
 
         // Write out new value or start dampening timer
         if (a->timeout_ms && a->timer) {
             crm_trace("Delayed write out (%dms) for %s", a->timeout_ms, attr);
             mainloop_timer_start(a->timer);
         } else {
             attrd_write_or_elect_attribute(a);
         }
 
     } else {
         if (is_force_write == 1 && a->timeout_ms && a->timer) {
             /* Save forced writing and set change flag. */
             /* The actual attribute is written by Writer after election. */
             crm_trace("Unchanged %s[%s] from %s is %s(Set the forced write flag)",
                       attr, host, peer->uname, value);
             a->force_write = TRUE;
         } else {
             crm_trace("Unchanged %s[%s] from %s is %s", attr, host, peer->uname, value);
         }
     }
 
     /* Set the seen flag for attribute processing held only in the own node. */
     v->seen = TRUE;
 
     /* If this is a cluster node whose node ID we are learning, remember it */
     if ((v->nodeid == 0) && (v->is_remote == FALSE)
         && (crm_element_value_int(xml, PCMK__XA_ATTR_NODE_ID,
                                   (int*)&v->nodeid) == 0) && (v->nodeid > 0)) {
         record_peer_nodeid(v, host);
     }
 }
 
 static void
 attrd_peer_update_one(const crm_node_t *peer, xmlNode *xml, bool filter)
 {
     attribute_t *a = NULL;
     const char *attr = crm_element_value(xml, PCMK__XA_ATTR_NAME);
     const char *value = crm_element_value(xml, PCMK__XA_ATTR_VALUE);
     const char *host = crm_element_value(xml, PCMK__XA_ATTR_NODE_NAME);
     int is_force_write = 0;
 
     if (attr == NULL) {
         crm_warn("Could not update attribute: peer did not specify name");
         return;
     }
 
     crm_element_value_int(xml, PCMK__XA_ATTR_FORCE, &is_force_write);
 
     a = attrd_populate_attribute(xml, attr);
     if (a == NULL) {
         return;
     }
 
     if (host == NULL) {
         // If no host was specified, update all hosts
         GHashTableIter vIter;
 
         crm_debug("Setting %s for all hosts to %s", attr, value);
         xml_remove_prop(xml, PCMK__XA_ATTR_NODE_ID);
         g_hash_table_iter_init(&vIter, a->values);
 
         while (g_hash_table_iter_next(&vIter, (gpointer *) & host, NULL)) {
             update_attr_on_host(a, peer, xml, attr, value, host, filter, is_force_write);
         }
 
     } else {
         // Update attribute value for the given host
         update_attr_on_host(a, peer, xml, attr, value, host, filter, is_force_write);
     }
 
     /* If this is a message from some attrd instance broadcasting its protocol
      * version, check to see if it's a new minimum version.
      */
     if (pcmk__str_eq(attr, CRM_ATTR_PROTOCOL, pcmk__str_none)) {
         attrd_update_minimum_protocol_ver(value);
     }
 }
 
 static void
 broadcast_unseen_local_values(void)
 {
     GHashTableIter aIter;
     GHashTableIter vIter;
     attribute_t *a = NULL;
     attribute_value_t *v = NULL;
     xmlNode *sync = NULL;
 
     g_hash_table_iter_init(&aIter, attributes);
     while (g_hash_table_iter_next(&aIter, NULL, (gpointer *) & a)) {
         g_hash_table_iter_init(&vIter, a->values);
         while (g_hash_table_iter_next(&vIter, NULL, (gpointer *) & v)) {
             if (!(v->seen) && pcmk__str_eq(v->nodename, attrd_cluster->uname,
                                            pcmk__str_casei)) {
                 if (sync == NULL) {
                     sync = create_xml_node(NULL, __func__);
                     crm_xml_add(sync, PCMK__XA_TASK, PCMK__ATTRD_CMD_SYNC_RESPONSE);
                 }
                 attrd_add_value_xml(sync, a, v, a->timeout_ms && a->timer);
             }
         }
     }
 
     if (sync != NULL) {
         crm_debug("Broadcasting local-only values");
-        attrd_send_message(NULL, sync);
+        attrd_send_message(NULL, sync, false);
         free_xml(sync);
     }
 }
 
 int
 attrd_cluster_connect(void)
 {
     attrd_cluster = calloc(1, sizeof(crm_cluster_t));
 
     attrd_cluster->destroy = attrd_cpg_destroy;
     attrd_cluster->cpg.cpg_deliver_fn = attrd_cpg_dispatch;
     attrd_cluster->cpg.cpg_confchg_fn = pcmk_cpg_membership;
 
     crm_set_status_callback(&attrd_peer_change_cb);
 
     if (crm_cluster_connect(attrd_cluster) == FALSE) {
         crm_err("Cluster connection failed");
         return -ENOTCONN;
     }
     return pcmk_ok;
 }
 
 void
 attrd_peer_clear_failure(pcmk__request_t *request)
 {
     xmlNode *xml = request->xml;
     const char *rsc = crm_element_value(xml, PCMK__XA_ATTR_RESOURCE);
     const char *host = crm_element_value(xml, PCMK__XA_ATTR_NODE_NAME);
     const char *op = crm_element_value(xml, PCMK__XA_ATTR_OPERATION);
     const char *interval_spec = crm_element_value(xml, PCMK__XA_ATTR_INTERVAL);
     guint interval_ms = crm_parse_interval_spec(interval_spec);
     char *attr = NULL;
     GHashTableIter iter;
     regex_t regex;
 
     crm_node_t *peer = crm_get_peer(0, request->peer);
 
     if (attrd_failure_regex(&regex, rsc, op, interval_ms) != pcmk_ok) {
         crm_info("Ignoring invalid request to clear failures for %s",
                  pcmk__s(rsc, "all resources"));
         return;
     }
 
     crm_xml_add(xml, PCMK__XA_TASK, PCMK__ATTRD_CMD_UPDATE);
 
     /* Make sure value is not set, so we delete */
     if (crm_element_value(xml, PCMK__XA_ATTR_VALUE)) {
         crm_xml_replace(xml, PCMK__XA_ATTR_VALUE, NULL);
     }
 
     g_hash_table_iter_init(&iter, attributes);
     while (g_hash_table_iter_next(&iter, (gpointer *) &attr, NULL)) {
         if (regexec(&regex, attr, 0, NULL, 0) == 0) {
             crm_trace("Matched %s when clearing %s",
                       attr, pcmk__s(rsc, "all resources"));
             crm_xml_add(xml, PCMK__XA_ATTR_NAME, attr);
             attrd_peer_update(peer, xml, host, false);
         }
     }
     regfree(&regex);
 }
 
 /*!
  * \internal
  * \brief Load attributes from a peer sync response
  *
  * \param[in]     peer      Peer that sent clear request
  * \param[in]     peer_won  Whether peer is the attribute writer
  * \param[in,out] xml       Request XML
  */
 void
 attrd_peer_sync_response(const crm_node_t *peer, bool peer_won, xmlNode *xml)
 {
     crm_info("Processing " PCMK__ATTRD_CMD_SYNC_RESPONSE " from %s",
              peer->uname);
 
     if (peer_won) {
         /* Initialize the "seen" flag for all attributes to cleared, so we can
          * detect attributes that local node has but the writer doesn't.
          */
         attrd_clear_value_seen();
     }
 
     // Process each attribute update in the sync response
     for (xmlNode *child = pcmk__xml_first_child(xml); child != NULL;
          child = pcmk__xml_next(child)) {
         attrd_peer_update(peer, child,
                           crm_element_value(child, PCMK__XA_ATTR_NODE_NAME),
                           true);
     }
 
     if (peer_won) {
         /* If any attributes are still not marked as seen, the writer doesn't
          * know about them, so send all peers an update with them.
          */
         broadcast_unseen_local_values();
     }
 }
 
 /*!
  * \internal
  * \brief Remove all attributes and optionally peer cache entries for a node
  *
  * \param[in] host     Name of node to purge
  * \param[in] uncache  If true, remove node from peer caches
  * \param[in] source   Who requested removal (only used for logging)
  */
 void
 attrd_peer_remove(const char *host, bool uncache, const char *source)
 {
     attribute_t *a = NULL;
     GHashTableIter aIter;
 
     CRM_CHECK(host != NULL, return);
     crm_notice("Removing all %s attributes for peer %s", host, source);
 
     g_hash_table_iter_init(&aIter, attributes);
     while (g_hash_table_iter_next(&aIter, NULL, (gpointer *) & a)) {
         if(g_hash_table_remove(a->values, host)) {
             crm_debug("Removed %s[%s] for peer %s", a->id, host, source);
         }
     }
 
     if (uncache) {
         crm_remote_peer_cache_remove(host);
         reap_crm_member(0, host);
     }
 }
 
 void
 attrd_peer_sync(crm_node_t *peer, xmlNode *xml)
 {
     GHashTableIter aIter;
     GHashTableIter vIter;
 
     attribute_t *a = NULL;
     attribute_value_t *v = NULL;
     xmlNode *sync = create_xml_node(NULL, __func__);
 
     crm_xml_add(sync, PCMK__XA_TASK, PCMK__ATTRD_CMD_SYNC_RESPONSE);
 
     g_hash_table_iter_init(&aIter, attributes);
     while (g_hash_table_iter_next(&aIter, NULL, (gpointer *) & a)) {
         g_hash_table_iter_init(&vIter, a->values);
         while (g_hash_table_iter_next(&vIter, NULL, (gpointer *) & v)) {
             crm_debug("Syncing %s[%s] = %s to %s", a->id, v->nodename, v->current, peer?peer->uname:"everyone");
             attrd_add_value_xml(sync, a, v, false);
         }
     }
 
     crm_debug("Syncing values to %s", peer?peer->uname:"everyone");
-    attrd_send_message(peer, sync);
+    attrd_send_message(peer, sync, false);
     free_xml(sync);
 }
 
 void
 attrd_peer_update(const crm_node_t *peer, xmlNode *xml, const char *host,
                   bool filter)
 {
     bool handle_sync_point = false;
 
     if (xml_has_children(xml)) {
         for (xmlNode *child = first_named_child(xml, XML_ATTR_OP); child != NULL;
              child = crm_next_same_xml(child)) {
             /* Set the node name on the child message, assuming it isn't already. */
             if (crm_element_value(child, PCMK__XA_ATTR_NODE_NAME) == NULL) {
                 pcmk__xe_add_node(xml, host, 0);
             }
 
             attrd_peer_update_one(peer, child, filter);
 
             if (attrd_request_has_sync_point(child)) {
                 handle_sync_point = true;
             }
         }
 
     } else {
         attrd_peer_update_one(peer, xml, filter);
 
         if (attrd_request_has_sync_point(xml)) {
             handle_sync_point = true;
         }
     }
 
     /* If the update XML specified that the client wanted to wait for a sync
      * point, process that now.
      */
     if (handle_sync_point) {
         crm_debug("Hit local sync point for attribute update");
         attrd_ack_waitlist_clients(attrd_sync_point_local, xml);
     }
 }
diff --git a/daemons/attrd/attrd_ipc.c b/daemons/attrd/attrd_ipc.c
index 36d6962da6..2cca2125bf 100644
--- a/daemons/attrd/attrd_ipc.c
+++ b/daemons/attrd/attrd_ipc.c
@@ -1,512 +1,528 @@
 /*
  * Copyright 2004-2022 the Pacemaker project contributors
  *
  * The version control history for this file may have further details.
  *
  * This source code is licensed under the GNU General Public License version 2
  * or later (GPLv2+) WITHOUT ANY WARRANTY.
  */
 
 #include <crm_internal.h>
 
 #include <errno.h>
 #include <stdint.h>
 #include <stdlib.h>
 #include <sys/types.h>
 
 #include <crm/cluster.h>
 #include <crm/cluster/internal.h>
 #include <crm/msg_xml.h>
 #include <crm/common/acl_internal.h>
 #include <crm/common/ipc_internal.h>
 #include <crm/common/logging.h>
 #include <crm/common/results.h>
 #include <crm/common/strings_internal.h>
 #include <crm/common/util.h>
 
 #include "pacemaker-attrd.h"
 
 static qb_ipcs_service_t *ipcs = NULL;
 
 /*!
  * \internal
  * \brief Build the XML reply to a client query
  *
  * param[in] attr Name of requested attribute
  * param[in] host Name of requested host (or NULL for all hosts)
  *
  * \return New XML reply
  * \note Caller is responsible for freeing the resulting XML
  */
 static xmlNode *build_query_reply(const char *attr, const char *host)
 {
     xmlNode *reply = create_xml_node(NULL, __func__);
     attribute_t *a;
 
     if (reply == NULL) {
         return NULL;
     }
     crm_xml_add(reply, F_TYPE, T_ATTRD);
     crm_xml_add(reply, F_SUBTYPE, PCMK__ATTRD_CMD_QUERY);
     crm_xml_add(reply, PCMK__XA_ATTR_VERSION, ATTRD_PROTOCOL_VERSION);
 
     /* If desired attribute exists, add its value(s) to the reply */
     a = g_hash_table_lookup(attributes, attr);
     if (a) {
         attribute_value_t *v;
         xmlNode *host_value;
 
         crm_xml_add(reply, PCMK__XA_ATTR_NAME, attr);
 
         /* Allow caller to use "localhost" to refer to local node */
         if (pcmk__str_eq(host, "localhost", pcmk__str_casei)) {
             host = attrd_cluster->uname;
             crm_trace("Mapped localhost to %s", host);
         }
 
         /* If a specific node was requested, add its value */
         if (host) {
             v = g_hash_table_lookup(a->values, host);
             host_value = create_xml_node(reply, XML_CIB_TAG_NODE);
             if (host_value == NULL) {
                 free_xml(reply);
                 return NULL;
             }
             pcmk__xe_add_node(host_value, host, 0);
             crm_xml_add(host_value, PCMK__XA_ATTR_VALUE,
                         (v? v->current : NULL));
 
         /* Otherwise, add all nodes' values */
         } else {
             GHashTableIter iter;
 
             g_hash_table_iter_init(&iter, a->values);
             while (g_hash_table_iter_next(&iter, NULL, (gpointer *) &v)) {
                 host_value = create_xml_node(reply, XML_CIB_TAG_NODE);
                 if (host_value == NULL) {
                     free_xml(reply);
                     return NULL;
                 }
                 pcmk__xe_add_node(host_value, v->nodename, 0);
                 crm_xml_add(host_value, PCMK__XA_ATTR_VALUE, v->current);
             }
         }
     }
     return reply;
 }
 
 xmlNode *
 attrd_client_clear_failure(pcmk__request_t *request)
 {
     xmlNode *xml = request->xml;
     const char *rsc, *op, *interval_spec;
 
     if (minimum_protocol_version >= 2) {
         /* Propagate to all peers (including ourselves).
          * This ends up at attrd_peer_message().
          */
-        attrd_send_message(NULL, xml);
+        attrd_send_message(NULL, xml, false);
         pcmk__set_result(&request->result, CRM_EX_OK, PCMK_EXEC_DONE, NULL);
         return NULL;
     }
 
     rsc = crm_element_value(xml, PCMK__XA_ATTR_RESOURCE);
     op = crm_element_value(xml, PCMK__XA_ATTR_OPERATION);
     interval_spec = crm_element_value(xml, PCMK__XA_ATTR_INTERVAL);
 
     /* Map this to an update */
     crm_xml_add(xml, PCMK__XA_TASK, PCMK__ATTRD_CMD_UPDATE);
 
     /* Add regular expression matching desired attributes */
 
     if (rsc) {
         char *pattern;
 
         if (op == NULL) {
             pattern = crm_strdup_printf(ATTRD_RE_CLEAR_ONE, rsc);
 
         } else {
             guint interval_ms = crm_parse_interval_spec(interval_spec);
 
             pattern = crm_strdup_printf(ATTRD_RE_CLEAR_OP,
                                         rsc, op, interval_ms);
         }
 
         crm_xml_add(xml, PCMK__XA_ATTR_PATTERN, pattern);
         free(pattern);
 
     } else {
         crm_xml_add(xml, PCMK__XA_ATTR_PATTERN, ATTRD_RE_CLEAR_ALL);
     }
 
     /* Make sure attribute and value are not set, so we delete via regex */
     if (crm_element_value(xml, PCMK__XA_ATTR_NAME)) {
         crm_xml_replace(xml, PCMK__XA_ATTR_NAME, NULL);
     }
     if (crm_element_value(xml, PCMK__XA_ATTR_VALUE)) {
         crm_xml_replace(xml, PCMK__XA_ATTR_VALUE, NULL);
     }
 
     return attrd_client_update(request);
 }
 
 xmlNode *
 attrd_client_peer_remove(pcmk__request_t *request)
 {
     xmlNode *xml = request->xml;
 
     // Host and ID are not used in combination, rather host has precedence
     const char *host = crm_element_value(xml, PCMK__XA_ATTR_NODE_NAME);
     char *host_alloc = NULL;
 
     attrd_send_ack(request->ipc_client, request->ipc_id, request->ipc_flags);
 
     if (host == NULL) {
         int nodeid = 0;
 
         crm_element_value_int(xml, PCMK__XA_ATTR_NODE_ID, &nodeid);
         if (nodeid > 0) {
             crm_node_t *node = pcmk__search_cluster_node_cache(nodeid, NULL);
             char *host_alloc = NULL;
 
             if (node && node->uname) {
                 // Use cached name if available
                 host = node->uname;
             } else {
                 // Otherwise ask cluster layer
                 host_alloc = get_node_name(nodeid);
                 host = host_alloc;
             }
             pcmk__xe_add_node(xml, host, 0);
         }
     }
 
     if (host) {
         crm_info("Client %s is requesting all values for %s be removed",
                  pcmk__client_name(request->ipc_client), host);
-        attrd_send_message(NULL, xml); /* ends up at attrd_peer_message() */
+        attrd_send_message(NULL, xml, false); /* ends up at attrd_peer_message() */
         free(host_alloc);
     } else {
         crm_info("Ignoring request by client %s to remove all peer values without specifying peer",
                  pcmk__client_name(request->ipc_client));
     }
 
     pcmk__set_result(&request->result, CRM_EX_OK, PCMK_EXEC_DONE, NULL);
     return NULL;
 }
 
 xmlNode *
 attrd_client_query(pcmk__request_t *request)
 {
     xmlNode *query = request->xml;
     xmlNode *reply = NULL;
     const char *attr = NULL;
 
     crm_debug("Query arrived from %s", pcmk__client_name(request->ipc_client));
 
     /* Request must specify attribute name to query */
     attr = crm_element_value(query, PCMK__XA_ATTR_NAME);
     if (attr == NULL) {
         pcmk__format_result(&request->result, CRM_EX_ERROR, PCMK_EXEC_ERROR,
                             "Ignoring malformed query from %s (no attribute name given)",
                             pcmk__client_name(request->ipc_client));
         return NULL;
     }
 
     /* Build the XML reply */
     reply = build_query_reply(attr, crm_element_value(query,
                                                       PCMK__XA_ATTR_NODE_NAME));
     if (reply == NULL) {
         pcmk__format_result(&request->result, CRM_EX_ERROR, PCMK_EXEC_ERROR,
                             "Could not respond to query from %s: could not create XML reply",
                             pcmk__client_name(request->ipc_client));
         return NULL;
     } else {
         pcmk__set_result(&request->result, CRM_EX_OK, PCMK_EXEC_DONE, NULL);
     }
 
     request->ipc_client->request_id = 0;
     return reply;
 }
 
 xmlNode *
 attrd_client_refresh(pcmk__request_t *request)
 {
     crm_info("Updating all attributes");
 
     attrd_send_ack(request->ipc_client, request->ipc_id, request->ipc_flags);
     attrd_write_attributes(true, true);
 
     pcmk__set_result(&request->result, CRM_EX_OK, PCMK_EXEC_DONE, NULL);
     return NULL;
 }
 
 xmlNode *
 attrd_client_update(pcmk__request_t *request)
 {
     xmlNode *xml = request->xml;
     attribute_t *a = NULL;
     char *host;
     const char *attr, *value, *regex;
 
     /* If the message has children, that means it is a message from a newer
      * client that supports sending multiple operations at a time.  There are
      * two ways we can handle that.
      */
     if (xml_has_children(xml)) {
         if (minimum_protocol_version >= 4) {
             /* First, if all peers support a certain protocol version, we can
              * just broadcast the big message and they'll handle it.
              */
-            attrd_send_message(NULL, xml);
+            attrd_send_message(NULL, xml, false);
             pcmk__set_result(&request->result, CRM_EX_OK, PCMK_EXEC_DONE, NULL);
         } else {
             /* Second, if they do not support that protocol version, split it
              * up into individual messages and call attrd_client_update on
              * each one.
              */
             for (xmlNode *child = first_named_child(xml, XML_ATTR_OP); child != NULL;
                  child = crm_next_same_xml(child)) {
                 request->xml = child;
                 /* Calling pcmk__set_result is handled by one of these calls to
                  * attrd_client_update, so no need to do it again here.
                  */
                 attrd_client_update(request);
             }
         }
 
         return NULL;
     }
 
     host = crm_element_value_copy(xml, PCMK__XA_ATTR_NODE_NAME);
     attr = crm_element_value(xml, PCMK__XA_ATTR_NAME);
     value = crm_element_value(xml, PCMK__XA_ATTR_VALUE);
     regex = crm_element_value(xml, PCMK__XA_ATTR_PATTERN);
 
     /* If a regex was specified, broadcast a message for each match */
     if ((attr == NULL) && regex) {
         GHashTableIter aIter;
         regex_t *r_patt = calloc(1, sizeof(regex_t));
 
         crm_debug("Setting %s to %s", regex, value);
         if (regcomp(r_patt, regex, REG_EXTENDED|REG_NOSUB)) {
             pcmk__format_result(&request->result, CRM_EX_ERROR, PCMK_EXEC_ERROR,
                                 "Bad regex '%s' for update from client %s", regex,
                                 pcmk__client_name(request->ipc_client));
 
         } else {
             g_hash_table_iter_init(&aIter, attributes);
             while (g_hash_table_iter_next(&aIter, (gpointer *) & attr, NULL)) {
                 int status = regexec(r_patt, attr, 0, NULL, 0);
 
                 if (status == 0) {
                     crm_trace("Matched %s with %s", attr, regex);
                     crm_xml_add(xml, PCMK__XA_ATTR_NAME, attr);
-                    attrd_send_message(NULL, xml);
+                    attrd_send_message(NULL, xml, false);
                 }
             }
 
             pcmk__set_result(&request->result, CRM_EX_OK, PCMK_EXEC_DONE, NULL);
         }
 
         free(host);
         regfree(r_patt);
         free(r_patt);
         return NULL;
 
     } else if (attr == NULL) {
         crm_err("Update request did not specify attribute or regular expression");
         pcmk__format_result(&request->result, CRM_EX_ERROR, PCMK_EXEC_ERROR,
                             "Client %s update request did not specify attribute or regular expression",
                             pcmk__client_name(request->ipc_client));
         free(host);
         return NULL;
     }
 
     if (host == NULL) {
         crm_trace("Inferring host");
         host = strdup(attrd_cluster->uname);
         pcmk__xe_add_node(xml, host, attrd_cluster->nodeid);
     }
 
     a = g_hash_table_lookup(attributes, attr);
 
     if (a == NULL && pcmk__str_eq(request->op, PCMK__ATTRD_CMD_UPDATE_DELAY, pcmk__str_none)) {
         pcmk__format_result(&request->result, CRM_EX_NOSUCH, PCMK_EXEC_ERROR,
                             "Attribute %s does not exist", attr);
         free(host);
         return NULL;
     }
 
     /* If value was specified using ++ or += notation, expand to real value */
     if (value) {
         if (attrd_value_needs_expansion(value)) {
             int int_value;
             attribute_value_t *v = NULL;
 
             if (a) {
                 v = g_hash_table_lookup(a->values, host);
             }
             int_value = attrd_expand_value(value, (v? v->current : NULL));
 
             crm_info("Expanded %s=%s to %d", attr, value, int_value);
             crm_xml_add_int(xml, PCMK__XA_ATTR_VALUE, int_value);
 
             /* Replacing the value frees the previous memory, so re-query it */
             value = crm_element_value(xml, PCMK__XA_ATTR_VALUE);
         }
     }
 
     crm_debug("Broadcasting %s[%s]=%s%s", attr, host, value,
               (attrd_election_won()? " (writer)" : ""));
 
     free(host);
 
-    attrd_send_message(NULL, xml); /* ends up at attrd_peer_message() */
+    if (pcmk__str_eq(attrd_request_sync_point(xml), PCMK__VALUE_CLUSTER, pcmk__str_none)) {
+        /* The client is waiting on the cluster-wide sync point.  In this case,
+         * the response ACK is not sent until this attrd broadcasts the update
+         * and receives its own confirmation back from all peers.
+         */
+        attrd_send_message(NULL, xml, true); /* ends up at attrd_peer_message() */
+
+    } else {
+        /* The client is either waiting on the local sync point or was not
+         * waiting on any sync point at all.  For the local sync point, the
+         * response ACK is sent in attrd_peer_update.  For clients not
+         * waiting on any sync point, the response ACK is sent in
+         * handle_update_request immediately before this function was called.
+         */
+        attrd_send_message(NULL, xml, false); /* ends up at attrd_peer_message() */
+    }
+
     pcmk__set_result(&request->result, CRM_EX_OK, PCMK_EXEC_DONE, NULL);
     return NULL;
 }
 
 /*!
  * \internal
  * \brief Accept a new client IPC connection
  *
  * \param[in,out] c    New connection
  * \param[in]     uid  Client user id
  * \param[in]     gid  Client group id
  *
  * \return pcmk_ok on success, -errno otherwise
  */
 static int32_t
 attrd_ipc_accept(qb_ipcs_connection_t *c, uid_t uid, gid_t gid)
 {
     crm_trace("New client connection %p", c);
     if (attrd_shutting_down()) {
         crm_info("Ignoring new connection from pid %d during shutdown",
                  pcmk__client_pid(c));
         return -EPERM;
     }
 
     if (pcmk__new_client(c, uid, gid) == NULL) {
         return -EIO;
     }
     return pcmk_ok;
 }
 
 /*!
  * \internal
  * \brief Destroy a client IPC connection
  *
  * \param[in] c  Connection to destroy
  *
  * \return FALSE (i.e. do not re-run this callback)
  */
 static int32_t
 attrd_ipc_closed(qb_ipcs_connection_t *c)
 {
     pcmk__client_t *client = pcmk__find_client(c);
 
     if (client == NULL) {
         crm_trace("Ignoring request to clean up unknown connection %p", c);
     } else {
         crm_trace("Cleaning up closed client connection %p", c);
 
         /* Remove the client from the sync point waitlist if it's present. */
         attrd_remove_client_from_waitlist(client);
 
         pcmk__free_client(client);
     }
 
     return FALSE;
 }
 
 /*!
  * \internal
  * \brief Destroy a client IPC connection
  *
  * \param[in,out] c  Connection to destroy
  *
  * \note We handle a destroyed connection the same as a closed one,
  *       but we need a separate handler because the return type is different.
  */
 static void
 attrd_ipc_destroy(qb_ipcs_connection_t *c)
 {
     crm_trace("Destroying client connection %p", c);
     attrd_ipc_closed(c);
 }
 
 static int32_t
 attrd_ipc_dispatch(qb_ipcs_connection_t * c, void *data, size_t size)
 {
     uint32_t id = 0;
     uint32_t flags = 0;
     pcmk__client_t *client = pcmk__find_client(c);
     xmlNode *xml = NULL;
 
     // Sanity-check, and parse XML from IPC data
     CRM_CHECK((c != NULL) && (client != NULL), return 0);
     if (data == NULL) {
         crm_debug("No IPC data from PID %d", pcmk__client_pid(c));
         return 0;
     }
 
     xml = pcmk__client_data2xml(client, data, &id, &flags);
 
     if (xml == NULL) {
         crm_debug("Unrecognizable IPC data from PID %d", pcmk__client_pid(c));
         pcmk__ipc_send_ack(client, id, flags, "ack", NULL, CRM_EX_PROTOCOL);
         return 0;
 
     } else {
         pcmk__request_t request = {
             .ipc_client     = client,
             .ipc_id         = id,
             .ipc_flags      = flags,
             .peer           = NULL,
             .xml            = xml,
             .call_options   = 0,
             .result         = PCMK__UNKNOWN_RESULT,
         };
 
         CRM_ASSERT(client->user != NULL);
         pcmk__update_acl_user(xml, PCMK__XA_ATTR_USER, client->user);
 
         request.op = crm_element_value_copy(request.xml, PCMK__XA_TASK);
         CRM_CHECK(request.op != NULL, return 0);
 
         attrd_handle_request(&request);
         pcmk__reset_request(&request);
     }
 
     free_xml(xml);
     return 0;
 }
 
 static struct qb_ipcs_service_handlers ipc_callbacks = {
     .connection_accept = attrd_ipc_accept,
     .connection_created = NULL,
     .msg_process = attrd_ipc_dispatch,
     .connection_closed = attrd_ipc_closed,
     .connection_destroyed = attrd_ipc_destroy
 };
 
 void
 attrd_ipc_fini(void)
 {
     if (ipcs != NULL) {
         pcmk__drop_all_clients(ipcs);
         qb_ipcs_destroy(ipcs);
         ipcs = NULL;
     }
 }
 
 /*!
  * \internal
  * \brief Set up attrd IPC communication
  */
 void
 attrd_init_ipc(void)
 {
     pcmk__serve_attrd_ipc(&ipcs, &ipc_callbacks);
 }
diff --git a/daemons/attrd/attrd_messages.c b/daemons/attrd/attrd_messages.c
index 3ba14a69b6..78df0d09a8 100644
--- a/daemons/attrd/attrd_messages.c
+++ b/daemons/attrd/attrd_messages.c
@@ -1,294 +1,301 @@
 /*
  * Copyright 2022 the Pacemaker project contributors
  *
  * The version control history for this file may have further details.
  *
  * This source code is licensed under the GNU General Public License version 2
  * or later (GPLv2+) WITHOUT ANY WARRANTY.
  */
 
 #include <crm_internal.h>
 
 #include <glib.h>
 
 #include <crm/common/messages_internal.h>
 #include <crm/msg_xml.h>
 
 #include "pacemaker-attrd.h"
 
 int minimum_protocol_version = -1;
 
 static GHashTable *attrd_handlers = NULL;
 
 static xmlNode *
 handle_unknown_request(pcmk__request_t *request)
 {
     crm_err("Unknown IPC request %s from %s %s",
             request->op, pcmk__request_origin_type(request),
             pcmk__request_origin(request));
     pcmk__format_result(&request->result, CRM_EX_PROTOCOL, PCMK_EXEC_INVALID,
                         "Unknown request type '%s' (bug?)", request->op);
     return NULL;
 }
 
 static xmlNode *
 handle_clear_failure_request(pcmk__request_t *request)
 {
     if (request->peer != NULL) {
         /* It is not currently possible to receive this as a peer command,
          * but will be, if we one day enable propagating this operation.
          */
         attrd_peer_clear_failure(request);
         pcmk__set_result(&request->result, CRM_EX_OK, PCMK_EXEC_DONE, NULL);
         return NULL;
     } else {
         if (attrd_request_has_sync_point(request->xml)) {
             /* If this client supplied a sync point it wants to wait for, add it to
              * the wait list.  Clients on this list will not receive an ACK until
              * their sync point is hit which will result in the client stalled there
              * until it receives a response.
              *
              * All other clients will receive the expected response as normal.
              */
             attrd_add_client_to_waitlist(request);
 
         } else {
             /* If the client doesn't want to wait for a sync point, go ahead and send
              * the ACK immediately.  Otherwise, we'll send the ACK when the appropriate
              * sync point is reached.
              */
             attrd_send_ack(request->ipc_client, request->ipc_id,
                            request->ipc_flags);
         }
 
         return attrd_client_clear_failure(request);
     }
 }
 
 static xmlNode *
 handle_flush_request(pcmk__request_t *request)
 {
     if (request->peer != NULL) {
         /* Ignore. The flush command was removed in 2.0.0 but may be
          * received from peers running older versions.
          */
         pcmk__set_result(&request->result, CRM_EX_OK, PCMK_EXEC_DONE, NULL);
         return NULL;
     } else {
         return handle_unknown_request(request);
     }
 }
 
 static xmlNode *
 handle_query_request(pcmk__request_t *request)
 {
     if (request->peer != NULL) {
         return handle_unknown_request(request);
     } else {
         return attrd_client_query(request);
     }
 }
 
 static xmlNode *
 handle_remove_request(pcmk__request_t *request)
 {
     if (request->peer != NULL) {
         const char *host = crm_element_value(request->xml, PCMK__XA_ATTR_NODE_NAME);
         attrd_peer_remove(host, true, request->peer);
         pcmk__set_result(&request->result, CRM_EX_OK, PCMK_EXEC_DONE, NULL);
         return NULL;
     } else {
         return attrd_client_peer_remove(request);
     }
 }
 
 static xmlNode *
 handle_refresh_request(pcmk__request_t *request)
 {
     if (request->peer != NULL) {
         return handle_unknown_request(request);
     } else {
         return attrd_client_refresh(request);
     }
 }
 
 static xmlNode *
 handle_sync_request(pcmk__request_t *request)
 {
     if (request->peer != NULL) {
         crm_node_t *peer = crm_get_peer(0, request->peer);
 
         attrd_peer_sync(peer, request->xml);
         pcmk__set_result(&request->result, CRM_EX_OK, PCMK_EXEC_DONE, NULL);
         return NULL;
     } else {
         return handle_unknown_request(request);
     }
 }
 
 static xmlNode *
 handle_sync_response_request(pcmk__request_t *request)
 {
     if (request->ipc_client != NULL) {
         return handle_unknown_request(request);
     } else {
         if (request->peer != NULL) {
             crm_node_t *peer = crm_get_peer(0, request->peer);
             bool peer_won = attrd_check_for_new_writer(peer, request->xml);
 
             if (!pcmk__str_eq(peer->uname, attrd_cluster->uname, pcmk__str_casei)) {
                 attrd_peer_sync_response(peer, peer_won, request->xml);
             }
         }
 
         pcmk__set_result(&request->result, CRM_EX_OK, PCMK_EXEC_DONE, NULL);
         return NULL;
     }
 }
 
 static xmlNode *
 handle_update_request(pcmk__request_t *request)
 {
     if (request->peer != NULL) {
         const char *host = crm_element_value(request->xml, PCMK__XA_ATTR_NODE_NAME);
         crm_node_t *peer = crm_get_peer(0, request->peer);
 
         attrd_peer_update(peer, request->xml, host, false);
         pcmk__set_result(&request->result, CRM_EX_OK, PCMK_EXEC_DONE, NULL);
         return NULL;
 
     } else {
         if (attrd_request_has_sync_point(request->xml)) {
             /* If this client supplied a sync point it wants to wait for, add it to
              * the wait list.  Clients on this list will not receive an ACK until
              * their sync point is hit which will result in the client stalled there
              * until it receives a response.
              *
              * All other clients will receive the expected response as normal.
              */
             attrd_add_client_to_waitlist(request);
 
         } else {
             /* If the client doesn't want to wait for a sync point, go ahead and send
              * the ACK immediately.  Otherwise, we'll send the ACK when the appropriate
              * sync point is reached.
              *
              * In the normal case, attrd_client_update can be called recursively which
              * makes where to send the ACK tricky.  Doing it here ensures the client
              * only ever receives one.
              */
             attrd_send_ack(request->ipc_client, request->ipc_id,
                            request->flags|crm_ipc_client_response);
         }
 
         return attrd_client_update(request);
     }
 }
 
 static void
 attrd_register_handlers(void)
 {
     pcmk__server_command_t handlers[] = {
         { PCMK__ATTRD_CMD_CLEAR_FAILURE, handle_clear_failure_request },
         { PCMK__ATTRD_CMD_FLUSH, handle_flush_request },
         { PCMK__ATTRD_CMD_PEER_REMOVE, handle_remove_request },
         { PCMK__ATTRD_CMD_QUERY, handle_query_request },
         { PCMK__ATTRD_CMD_REFRESH, handle_refresh_request },
         { PCMK__ATTRD_CMD_SYNC, handle_sync_request },
         { PCMK__ATTRD_CMD_SYNC_RESPONSE, handle_sync_response_request },
         { PCMK__ATTRD_CMD_UPDATE, handle_update_request },
         { PCMK__ATTRD_CMD_UPDATE_DELAY, handle_update_request },
         { PCMK__ATTRD_CMD_UPDATE_BOTH, handle_update_request },
         { NULL, handle_unknown_request },
     };
 
     attrd_handlers = pcmk__register_handlers(handlers);
 }
 
 void
 attrd_unregister_handlers(void)
 {
     if (attrd_handlers != NULL) {
         g_hash_table_destroy(attrd_handlers);
         attrd_handlers = NULL;
     }
 }
 
 void
 attrd_handle_request(pcmk__request_t *request)
 {
     xmlNode *reply = NULL;
     char *log_msg = NULL;
     const char *reason = NULL;
 
     if (attrd_handlers == NULL) {
         attrd_register_handlers();
     }
 
     reply = pcmk__process_request(request, attrd_handlers);
 
     if (reply != NULL) {
         crm_log_xml_trace(reply, "Reply");
 
         if (request->ipc_client != NULL) {
             pcmk__ipc_send_xml(request->ipc_client, request->ipc_id, reply,
                                request->ipc_flags);
         } else {
             crm_err("Not sending CPG reply to client");
         }
 
         free_xml(reply);
     }
 
     reason = request->result.exit_reason;
     log_msg = crm_strdup_printf("Processed %s request from %s %s: %s%s%s%s",
                                 request->op, pcmk__request_origin_type(request),
                                 pcmk__request_origin(request),
                                 pcmk_exec_status_str(request->result.execution_status),
                                 (reason == NULL)? "" : " (",
                                 pcmk__s(reason, ""),
                                 (reason == NULL)? "" : ")");
 
     if (!pcmk__result_ok(&request->result)) {
         crm_warn("%s", log_msg);
     } else {
         crm_debug("%s", log_msg);
     }
 
     free(log_msg);
     pcmk__reset_request(request);
 }
 
 /*!
     \internal
     \brief Broadcast private attribute for local node with protocol version
 */
 void
 attrd_broadcast_protocol(void)
 {
     xmlNode *attrd_op = create_xml_node(NULL, __func__);
 
     crm_xml_add(attrd_op, F_TYPE, T_ATTRD);
     crm_xml_add(attrd_op, F_ORIG, crm_system_name);
     crm_xml_add(attrd_op, PCMK__XA_TASK, PCMK__ATTRD_CMD_UPDATE);
     crm_xml_add(attrd_op, PCMK__XA_ATTR_NAME, CRM_ATTR_PROTOCOL);
     crm_xml_add(attrd_op, PCMK__XA_ATTR_VALUE, ATTRD_PROTOCOL_VERSION);
     crm_xml_add_int(attrd_op, PCMK__XA_ATTR_IS_PRIVATE, 1);
     pcmk__xe_add_node(attrd_op, attrd_cluster->uname, attrd_cluster->nodeid);
 
     crm_debug("Broadcasting attrd protocol version %s for node %s",
               ATTRD_PROTOCOL_VERSION, attrd_cluster->uname);
 
-    attrd_send_message(NULL, attrd_op); /* ends up at attrd_peer_message() */
+    attrd_send_message(NULL, attrd_op, false); /* ends up at attrd_peer_message() */
 
     free_xml(attrd_op);
 }
 
 gboolean
-attrd_send_message(crm_node_t * node, xmlNode * data)
+attrd_send_message(crm_node_t *node, xmlNode *data, bool confirm)
 {
     crm_xml_add(data, F_TYPE, T_ATTRD);
     crm_xml_add(data, PCMK__XA_ATTR_VERSION, ATTRD_PROTOCOL_VERSION);
+
+    /* Request a confirmation from the destination peer node (which could
+     * be all if node is NULL) that the message has been received and
+     * acted upon.
+     */
+    pcmk__xe_set_bool_attr(data, PCMK__XA_CONFIRM, confirm);
+
     attrd_xml_add_writer(data);
     return send_cluster_message(node, crm_msg_attrd, data, TRUE);
 }
diff --git a/daemons/attrd/pacemaker-attrd.h b/daemons/attrd/pacemaker-attrd.h
index 537bf85b8c..25f7c8a5e1 100644
--- a/daemons/attrd/pacemaker-attrd.h
+++ b/daemons/attrd/pacemaker-attrd.h
@@ -1,197 +1,198 @@
 /*
  * Copyright 2013-2022 the Pacemaker project contributors
  *
  * The version control history for this file may have further details.
  *
  * This source code is licensed under the GNU General Public License version 2
  * or later (GPLv2+) WITHOUT ANY WARRANTY.
  */
 
 #ifndef PACEMAKER_ATTRD__H
 #  define PACEMAKER_ATTRD__H
 
 #include <regex.h>
 #include <glib.h>
 #include <crm/crm.h>
 #include <crm/cluster.h>
 #include <crm/cluster/election_internal.h>
 #include <crm/common/messages_internal.h>
 #include <crm/cib/internal.h>
 
 /*
  * Legacy attrd (all pre-1.1.11 Pacemaker versions, plus all versions when used
  * with the no-longer-supported CMAN or corosync-plugin stacks) is unversioned.
  *
  * With atomic attrd, each attrd will send ATTRD_PROTOCOL_VERSION with every
  * peer request and reply. As of Pacemaker 2.0.0, at start-up each attrd will
  * also set a private attribute for itself with its version, so any attrd can
  * determine the minimum version supported by all peers.
  *
  * Protocol  Pacemaker  Significant changes
  * --------  ---------  -------------------
  *     1       1.1.11   PCMK__ATTRD_CMD_UPDATE (PCMK__XA_ATTR_NAME only),
  *                      PCMK__ATTRD_CMD_PEER_REMOVE, PCMK__ATTRD_CMD_REFRESH,
  *                      PCMK__ATTRD_CMD_FLUSH, PCMK__ATTRD_CMD_SYNC,
  *                      PCMK__ATTRD_CMD_SYNC_RESPONSE
  *     1       1.1.13   PCMK__ATTRD_CMD_UPDATE (with PCMK__XA_ATTR_PATTERN),
  *                      PCMK__ATTRD_CMD_QUERY
  *     1       1.1.15   PCMK__ATTRD_CMD_UPDATE_BOTH,
  *                      PCMK__ATTRD_CMD_UPDATE_DELAY
  *     2       1.1.17   PCMK__ATTRD_CMD_CLEAR_FAILURE
  *     3       2.1.1    PCMK__ATTRD_CMD_SYNC_RESPONSE indicates remote nodes
- *     4       2.2.0    Multiple attributes can be updated in a single IPC
+ *     4       2.1.5    Multiple attributes can be updated in a single IPC
  *                      message
+ *     5       2.1.5    Peers can request confirmation of a sent message
  */
-#define ATTRD_PROTOCOL_VERSION "4"
+#define ATTRD_PROTOCOL_VERSION "5"
 
 #define attrd_send_ack(client, id, flags) \
     pcmk__ipc_send_ack((client), (id), (flags), "ack", ATTRD_PROTOCOL_VERSION, CRM_EX_INDETERMINATE)
 
 void attrd_init_mainloop(void);
 void attrd_run_mainloop(void);
 
 void attrd_set_requesting_shutdown(void);
 void attrd_clear_requesting_shutdown(void);
 void attrd_free_waitlist(void);
 bool attrd_requesting_shutdown(void);
 bool attrd_shutting_down(void);
 void attrd_shutdown(int nsig);
 void attrd_init_ipc(void);
 void attrd_ipc_fini(void);
 
 void attrd_cib_disconnect(void);
 
 bool attrd_value_needs_expansion(const char *value);
 int attrd_expand_value(const char *value, const char *old_value);
 
 /* regular expression to clear failures of all resources */
 #define ATTRD_RE_CLEAR_ALL \
     "^(" PCMK__FAIL_COUNT_PREFIX "|" PCMK__LAST_FAILURE_PREFIX ")-"
 
 /* regular expression to clear failure of all operations for one resource
  * (format takes resource name)
  *
  * @COMPAT attributes set < 1.1.17:
  * also match older attributes that do not have the operation part
  */
 #define ATTRD_RE_CLEAR_ONE ATTRD_RE_CLEAR_ALL "%s(#.+_[0-9]+)?$"
 
 /* regular expression to clear failure of one operation for one resource
  * (format takes resource name, operation name, and interval)
  *
  * @COMPAT attributes set < 1.1.17:
  * also match older attributes that do not have the operation part
  */
 #define ATTRD_RE_CLEAR_OP ATTRD_RE_CLEAR_ALL "%s(#%s_%u)?$"
 
 int attrd_failure_regex(regex_t *regex, const char *rsc, const char *op,
                         guint interval_ms);
 
 extern cib_t *the_cib;
 
 /* Alerts */
 
 extern lrmd_t *the_lrmd;
 extern crm_trigger_t *attrd_config_read;
 
 void attrd_lrmd_disconnect(void);
 gboolean attrd_read_options(gpointer user_data);
 void attrd_cib_replaced_cb(const char *event, xmlNode * msg);
 void attrd_cib_updated_cb(const char *event, xmlNode *msg);
 int attrd_send_attribute_alert(const char *node, int nodeid,
                                const char *attr, const char *value);
 
 // Elections
 void attrd_election_init(void);
 void attrd_election_fini(void);
 void attrd_start_election_if_needed(void);
 bool attrd_election_won(void);
 void attrd_handle_election_op(const crm_node_t *peer, xmlNode *xml);
 bool attrd_check_for_new_writer(const crm_node_t *peer, const xmlNode *xml);
 void attrd_declare_winner(void);
 void attrd_remove_voter(const crm_node_t *peer);
 void attrd_xml_add_writer(xmlNode *xml);
 
 typedef struct attribute_s {
     char *uuid; /* TODO: Remove if at all possible */
     char *id;
     char *set;
     GHashTable *values;
     int update;
     int timeout_ms;
 
     /* TODO: refactor these three as a bitmask */
     bool changed; /* whether attribute value has changed since last write */
     bool unknown_peer_uuids; /* whether we know we're missing a peer uuid */
     gboolean is_private; /* whether to keep this attribute out of the CIB */
 
     mainloop_timer_t *timer;
 
     char *user;
 
     gboolean force_write; /* Flag for updating attribute by ignoring delay */
 
 } attribute_t;
 
 typedef struct attribute_value_s {
         uint32_t nodeid;
         gboolean is_remote;
         char *nodename;
         char *current;
         char *requested;
         gboolean seen;
 } attribute_value_t;
 
 extern crm_cluster_t *attrd_cluster;
 extern GHashTable *attributes;
 
 #define CIB_OP_TIMEOUT_S 120
 
 int attrd_cluster_connect(void);
 void attrd_peer_update(const crm_node_t *peer, xmlNode *xml, const char *host,
                        bool filter);
 void attrd_peer_sync(crm_node_t *peer, xmlNode *xml);
 void attrd_peer_remove(const char *host, bool uncache, const char *source);
 void attrd_peer_clear_failure(pcmk__request_t *request);
 void attrd_peer_sync_response(const crm_node_t *peer, bool peer_won,
                               xmlNode *xml);
 
 void attrd_broadcast_protocol(void);
 xmlNode *attrd_client_peer_remove(pcmk__request_t *request);
 xmlNode *attrd_client_clear_failure(pcmk__request_t *request);
 xmlNode *attrd_client_update(pcmk__request_t *request);
 xmlNode *attrd_client_refresh(pcmk__request_t *request);
 xmlNode *attrd_client_query(pcmk__request_t *request);
-gboolean attrd_send_message(crm_node_t * node, xmlNode * data);
+gboolean attrd_send_message(crm_node_t *node, xmlNode *data, bool confirm);
 
 xmlNode *attrd_add_value_xml(xmlNode *parent, const attribute_t *a,
                              const attribute_value_t *v, bool force_write);
 void attrd_clear_value_seen(void);
 void attrd_free_attribute(gpointer data);
 void attrd_free_attribute_value(gpointer data);
 attribute_t *attrd_populate_attribute(xmlNode *xml, const char *attr);
 
 void attrd_write_attribute(attribute_t *a, bool ignore_delay);
 void attrd_write_attributes(bool all, bool ignore_delay);
 void attrd_write_or_elect_attribute(attribute_t *a);
 
 extern int minimum_protocol_version;
 void attrd_update_minimum_protocol_ver(const char *value);
 
 mainloop_timer_t *attrd_add_timer(const char *id, int timeout_ms, attribute_t *attr);
 
 void attrd_unregister_handlers(void);
 void attrd_handle_request(pcmk__request_t *request);
 
 enum attrd_sync_point {
     attrd_sync_point_local,
     attrd_sync_point_cluster,
 };
 
 void attrd_add_client_to_waitlist(pcmk__request_t *request);
 void attrd_ack_waitlist_clients(enum attrd_sync_point sync_point, const xmlNode *xml);
 void attrd_remove_client_from_waitlist(pcmk__client_t *client);
 const char *attrd_request_sync_point(xmlNode *xml);
 bool attrd_request_has_sync_point(xmlNode *xml);
 
 #endif /* PACEMAKER_ATTRD__H */
diff --git a/include/crm_internal.h b/include/crm_internal.h
index 08193c35b6..63a172690a 100644
--- a/include/crm_internal.h
+++ b/include/crm_internal.h
@@ -1,113 +1,114 @@
 /*
  * Copyright 2006-2021 the Pacemaker project contributors
  *
  * The version control history for this file may have further details.
  *
  * This source code is licensed under the GNU Lesser General Public License
  * version 2.1 or later (LGPLv2.1+) WITHOUT ANY WARRANTY.
  */
 
 #ifndef CRM_INTERNAL__H
 #  define CRM_INTERNAL__H
 
 #  ifndef PCMK__CONFIG_H
 #    define PCMK__CONFIG_H
 #    include <config.h>
 #  endif
 
 #  include <portability.h>
 
 /* Our minimum glib dependency is 2.42. Define that as both the minimum and
  * maximum glib APIs that are allowed (i.e. APIs that were already deprecated
  * in 2.42, and APIs introduced after 2.42, cannot be used by Pacemaker code).
  */
 #define GLIB_VERSION_MIN_REQUIRED GLIB_VERSION_2_42
 #define GLIB_VERSION_MAX_ALLOWED GLIB_VERSION_2_42
 
 #  include <glib.h>
 #  include <stdbool.h>
 #  include <libxml/tree.h>
 
 /* Public API headers can guard including deprecated API headers with this
  * symbol, thus preventing internal code (which includes this header) from using
  * deprecated APIs, while still allowing external code to use them by default.
  */
 #define PCMK_ALLOW_DEPRECATED 0
 
 #  include <crm/lrmd.h>
 #  include <crm/common/logging.h>
 #  include <crm/common/logging_internal.h>
 #  include <crm/common/ipc_internal.h>
 #  include <crm/common/options_internal.h>
 #  include <crm/common/output_internal.h>
 #  include <crm/common/xml_internal.h>
 #  include <crm/common/internal.h>
 #  include <locale.h>
 #  include <gettext.h>
 
 #define N_(String) (String)
 
 #ifdef ENABLE_NLS
 #  define _(String) gettext(String)
 #else
 #  define _(String) (String)
 #endif
 
 
 /*
  * XML attribute names used only by internal code
  */
 
 #define PCMK__XA_ATTR_DAMPENING         "attr_dampening"
 #define PCMK__XA_ATTR_FORCE             "attrd_is_force_write"
 #define PCMK__XA_ATTR_INTERVAL          "attr_clear_interval"
 #define PCMK__XA_ATTR_IS_PRIVATE        "attr_is_private"
 #define PCMK__XA_ATTR_IS_REMOTE         "attr_is_remote"
 #define PCMK__XA_ATTR_NAME              "attr_name"
 #define PCMK__XA_ATTR_NODE_ID           "attr_host_id"
 #define PCMK__XA_ATTR_NODE_NAME         "attr_host"
 #define PCMK__XA_ATTR_OPERATION         "attr_clear_operation"
 #define PCMK__XA_ATTR_PATTERN           "attr_regex"
 #define PCMK__XA_ATTR_RESOURCE          "attr_resource"
 #define PCMK__XA_ATTR_SECTION           "attr_section"
 #define PCMK__XA_ATTR_SET               "attr_set"
 #define PCMK__XA_ATTR_SYNC_POINT        "attr_sync_point"
 #define PCMK__XA_ATTR_USER              "attr_user"
 #define PCMK__XA_ATTR_UUID              "attr_key"
 #define PCMK__XA_ATTR_VALUE             "attr_value"
 #define PCMK__XA_ATTR_VERSION           "attr_version"
 #define PCMK__XA_ATTR_WRITER            "attr_writer"
 #define PCMK__XA_CONFIG_ERRORS          "config-errors"
 #define PCMK__XA_CONFIG_WARNINGS        "config-warnings"
+#define PCMK__XA_CONFIRM                "confirm"
 #define PCMK__XA_GRAPH_ERRORS           "graph-errors"
 #define PCMK__XA_GRAPH_WARNINGS         "graph-warnings"
 #define PCMK__XA_MODE                   "mode"
 #define PCMK__XA_TASK                   "task"
 
 
 /*
  * IPC service names that are only used internally
  */
 
 #  define PCMK__SERVER_BASED_RO		"cib_ro"
 #  define PCMK__SERVER_BASED_RW		"cib_rw"
 #  define PCMK__SERVER_BASED_SHM		"cib_shm"
 
 /*
  * IPC commands that can be sent to Pacemaker daemons
  */
 
 #define PCMK__ATTRD_CMD_PEER_REMOVE     "peer-remove"
 #define PCMK__ATTRD_CMD_UPDATE          "update"
 #define PCMK__ATTRD_CMD_UPDATE_BOTH     "update-both"
 #define PCMK__ATTRD_CMD_UPDATE_DELAY    "update-delay"
 #define PCMK__ATTRD_CMD_QUERY           "query"
 #define PCMK__ATTRD_CMD_REFRESH         "refresh"
 #define PCMK__ATTRD_CMD_FLUSH           "flush"
 #define PCMK__ATTRD_CMD_SYNC            "sync"
 #define PCMK__ATTRD_CMD_SYNC_RESPONSE   "sync-response"
 #define PCMK__ATTRD_CMD_CLEAR_FAILURE   "clear-failure"
 
 #define PCMK__CONTROLD_CMD_NODES        "list-nodes"
 
 #endif                          /* CRM_INTERNAL__H */